Hello all
Sorry if this is a duplicate, haven't found a thread with me specific
config (no UDP).
System:
ubuntu 12.10
N2100
SBX
GNU Radio 3.7.2.1
UHD 003.006.002-1
I have been trying to set up a video link (loop back cable) using named
pipes but am stuck with a crash.
It works until I introduce the USRP into the loop. Though it is the same
set up I use to transmit I text file without trouble.
What I have done:
VLC - Named Pipe - VLC
(fail) - found reference to VLC bugs in forums so gave up on that
VLC - Named Pipe - Mplayer
(works)
VLC - Named Pipe 1 - File Source GRC - File Sink GRC - Named Pipe 2 -
Mplayer
(works)
VLC - Named Pipe 1 - File Source GRC - OFDM MOD - OFDM DEMOD - File Sink
GRC - Named Pipe 2 - Mplayer
(works)
Now with hardware:
VLC - Named Pipe 1 - File Source GRC - OFDM MOD - USRP Sink- USRP -Source -
OFDM DEMOD - File Sink GRC - Named Pipe 2 - Mplayer
(FAILS!!). Reports: Segfault (core dumped). GRC file is running, VLC is
streaming. Fail occurs as soon as I open Named Pipe 2 with Mplayer
However, this is the identical GRC - USRP setup I use to repeatedly
transmit a text file successfully.
I have no reason to believe the UHDlib is failing, the segfault I think is
a python crash?
The parameters I am using:
VLC:
cvlc v4l2:///dev/video0 :v4l2-width=160 :v4l2-height=120
:v4l2-aspect-ratio=4/3 --noaudio
--sout="#transcode{vcodec=h264,vb=1024}:file{dst=./txPIPE.ts}" :sout-keep
USRP:
sample rate 12.5M
GRC: - not sure of the impact of these settings
These are the ones I am not so sure of:
File source, repeat yes or no?
File Sink, unbuffered on or off? append file on or off?
I am guessing my problem is related to sample rate, buffer sizes, frame
rate etc. I have tried a few permutations without luck though, but not
everything.
I have not set camera fps ->
*v4l2-fps <float>*I have hoped the data flow back pressure would be dealt
with by perhaps VLC with default setting (zero)? Or I'd just miss frames on
reception?
Just looking for some suggestions here I as I have put a good bit of time
into this now without luck....
regards
Alexander Buckley
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